alanhdu opened a new issue, #39927: URL: https://github.com/apache/arrow/issues/39927
### Describe the enhancement requested Currently, if you try to do something like: ```python a = pa.array([None, None, None]).cast(pa.dictionary(pa.int8(), pa.null())) b = pa.array([None, None, None]).cast(pa.dictionary(pa.int8(), pa.null())) pa.chunked_array([a, b]).unify_dictionaries() ``` PyArrow will raise an exception like: ``` File pyarrow/table.pxi:1206, in pyarrow.lib.ChunkedArray.unify_dictionaries() File pyarrow/error.pxi:154, in pyarrow.lib.pyarrow_internal_check_status() File pyarrow/error.pxi:91, in pyarrow.lib.check_status() ArrowNotImplementedError: Unification of null dictionaries is not implemented ``` Is there any way to just implement this? Manually calling `.combine_chunks()` seems to work fine, so the logic is clearly implemented somewhere. ``` a = pa.array([None, None, None]).cast(pa.dictionary(pa.int8(), pa.null())) b = pa.array([None, None, None]).cast(pa.dictionary(pa.int8(), pa.null())) pa.chunked_array([a, b]).combine_chunks() ``` I admit this might be a very niche feature (I am confused why I have feather files with these dictionary-encoded nulls, but I do and it'd be nice to be able to handle them). ### Versions I am testing this on Python 3.10 and pyarrow 15. ### Component(s) Python -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
